darken up
English
Verb
darken up (third-person singular simple present darkens up, present participle darkening up, simple past and past participle darkened up)
- (transitive, intransitive) To become or make (something) darker.
- Synonym of black up.
darken up (third-person singular simple present darkens up, present participle darkening up, simple past and past participle darkened up)